Description
With Stasis technology licensed from Threshold. This is the original version with design input from Nelson Pass. While the later II version also used Stasis technology, Mr. Pass stated in his Stereophile interview that his design was the original, not the later version. Excellent, working great from my personal system. Repainted top cover, near mint faceplate & heat sinks. Slight discoloration on rear panel, only visible under bright light. Appears updated with 4 resistors added to power supply (see 4 red units wired into capacitor leads). Has been in my system for 5 years, sounds wonderful, very smooth, runs cool (yes, green light shows when turned on, see last pic). I bought this unit while my main amp was being repaired, but I liked it so much that Ive kept it for 5 years. Drove difficult loads easily, including current hungry Martin Logan CLS, voltage hungry Avalon Ascent II. Also made a great bass amplifier for Infinity bass towers. Lights in the house dim upon turn on. I wish I could afford to keep it. Will be heavily packaged. Free local pickup from NW New Jersey zip 07825, Blairstown, off Rt 80 exit 12. Im willing to deliver or meet you up to 70 miles. Description: They (Nakamichi) recruit Nelson Pass (of Threshold) as a “hired gun” and combine his designs and circuit topology with their deep pockets and efficient production techniques. The result?… What is essentially a Threshold power amplifier but way better looking and less than half the price.They were supposed to just license his STASIS technology, which combines the benefits of Class A amplification without the drawbacks (runs stupid hot = very low reliability) into a hybrid Class A/Class AB power amplifier with optical bias. Well, they didn’t just license STASIS. Rather, the first generation of the PA-7 is a direct copy of the equivalent Threshold amp (S300 II). A lawsuit ensues, then Nakamichi releases the PA-7II with an altered design providing 25 more WPC (watts per channel) and a higher price tag. But everyone knew then and knows now that the original PA-7 was, “the one to get”. The PA-7 delivers 200 watts per channel, uses no overall negative feedback (a Pass trademark), and boasts the Stasis section, which consists of a low-power voltage amplifier coupled to the current mirror bootstrap output stage to do all the heavy lifting required for high-power output.Back in 1989, when Stereo Review featured the PA-7, writer Julian Hirsch measured the PA-7’s output at 253 watts into an 8-ohm load, 400 watts into a 4-ohm load, and 650 watts into two ohms. A quick look under the hood reveals why. A large 700 VA toroidal transformer and a bank of power supply capacitors totaling 132,000 µf proves the PA-7 means business. Such a setup made the PA-7 a perfect choice for demanding loudspeakers and, like the Threshold Stasis amplifiers, it ended up in many systems based around electrostatic speakers or Magnepans. Specs:Power output: 200 watts per channel into 8? (stereo) Frequency response: 20Hz to 20kHz Total harmonic distortion: 0.1% Damping factor: 60 Input sensitivity: 2V Signal to noise ratio: 120dB Semiconductors: 16 x output transistors per channel Dimensions: 435 x 200 x 421mm Weight: 27kg (59.5 lbs.)
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